Mothers and babies are being put at risk because consultants are too busy in meetings and working in clinics to spend enough time on the delivery wards, a study of senior doctors has revealed.

A survey by the Royal College of Obstetricians and Gynaecologists has also found that in one in 10 childbirth emergencies, midwives and junior staff do not bother to call consultants, contravening their own guidelines.

The latest figures come as an inquiry on the safety of Britain's maternity units is launched tomorrow by the health think tank, the King's Fund. The independent panel will look at whether hospitals are learning from previous experiences.

The government's inspectors, the Healthcare Commission, reported in August on the tragedies at Northwick Park Hospital, north London, where 10 mothers died in three years. The lack of senior staff present at births was found to be one of the key factors.

The royal college claims that in up to a quarter of all maternity units, senior obstetricians are not there for the minimum 40 hours a week needed to meet proper safety standards. The results of the study were presented last week at a conference.

Professor Martin Whittle, clinical co-director of the college's national collaborative centre for women's and children's health, said: 'In the past, consultants might pop their head round the door of a delivery unit, say "Hi, is everything OK?" and then leave. Now the senior involvement in the care of the sick mother and baby is no longer an option. It is sensible for someone experienced to deal with clinical problems and instruct trainees - 40 hours a week doesn't seem too much to ask.'

Professor Allan Templeton, college president, said: 'This is primarily a staffing problem of insufficient consultants who are too tied up in operating theatres or clinics to have a presence in the labour wards.'

According to Hospital Doctor magazine, some doctors feel the only way services can be improved is if there is a significant expansion of staff. One estimate is that some 2,500 extra consultants would be needed to provide full cover in maternity units across the country.

In Scotland, a recent study has shown that having more consultants reduces the complication rates. A three-year audit of 'near misses' in maternity units showed that one hospital stood out as having 10 major haemorrhages for every 1,000 deliveries, compared with the Scottish average of five per 1,000. It was found to have consultants present in just 49 per cent of deliveries, compared with the average of 76 per cent.

King's Fund chief executive Niall Dickson said: 'There are thousands of dedicated and skilled professionals and support staff who do a fantastic job every day in these services, sometimes working under considerable pressure. But there is also a widespread view that we can do better and we need to understand the challenges the service is facing. Our aim is to understand better the nature of the problem and to begin to find solutions. We hope this inquiry will make a real difference to the care and support mothers and babies receive.'